Introduction: We were interested in building on previous studies showing the promotive and buffering roles of social support for emerging adults. We tested the associations of multiple domains of social support (i.e., family, friends) with measures of adjustment and adversity. Methods: Across four studies, U.S. college adults reported on domains of social support (family, friends, significant other), psychological adjustment (i.e., life satisfaction, flourishing), and psychological adversity (i.e., recent stress, depressive symptoms). Studies 1 and 4 were cross-sectional, whereas Studies 2 and 3 involved two, monthly survey reports. Study 4 was completed against the backdrop of early COVID-19 disruptions for college adults in the Spring of 2020. Results: In each study, each domain of social support was positively correlated with measures of adjustment and negatively correlated with measures of adversity. Partial correlations indicated that support from friends was incrementally associated with nearly every outcome, whereas support from family was incrementally associated with a majority of outcomes. Multiphase studies supported unidirectional, but not bidirectional, effects from earlier adjustment onto later social support. Discussion: Overall, findings reinforce the importance of social support for young adults and highlight the distinct importance of family and friends. Findings also suggest that a lack of perceived social support may contribute to risks fitting views such as the stress generation theory among emerging adults.